KR20230054608A - Negative electrode plates, secondary batteries, battery modules, battery packs and electrical devices - Google Patents

Abstract

The present invention provides a negative electrode plate, a secondary battery, a battery module, a battery pack, and an electric device. The negative electrode plate includes a first coating layer, a second coating layer, and a current collector, one side of the second coating layer is the current collector, and the other side of the second coating layer is the first coating layer, and the first coating layer and the first coating layer are the current collector. 2 The coating layer includes a silicon-based material. The mole ratio of O element and Si element of the silicon-based material of the first coating layer is 0.5 to 1.5, and the mole ratio of O element and Si element of the silicon-based material of the second coating layer is 0.3 or less. The present invention can improve the cycle life and energy density of the battery.

Description

Negative electrode plates, secondary batteries, battery modules, battery packs and electrical devices

The present invention relates to the field of lithium batteries, and more particularly to negative electrode plates, secondary batteries, battery modules, battery packs and electric devices.

Lithium-ion batteries have characteristics such as high specific energy, high operating voltage, low self-discharge rate, small volume, and light weight. With the rapid development of electric vehicles, people have higher and higher requirements for the energy density and cycle performance of lithium ion batteries. Silicon-based materials have become ideal materials for next-generation lithium-ion anode materials due to their high specific capacity characteristics.

Silicon-based materials have a large volume change during the lithium deintercalation process, which affects the cycle life of a lithium ion battery, and silicon-based materials have a low primary coulombic efficiency, which affects the energy density of a lithium ion battery.

The present invention has been devised in view of the above problems, and aims to improve the cycle life and energy density of lithium ion batteries.

To achieve the above object, the present invention provides a negative electrode plate, a secondary battery, a battery module, a battery pack and an electric device.

A first aspect of the present invention provides a negative electrode plate including a first coating layer, a second coating layer, and a current collector. One side of the second coating layer is the current collector, the other side of the second coating layer is the first coating layer, and the first coating layer and the second coating layer include a silicon-based material. The mole ratio of O element and Si element of the silicon-based material of the first coating layer is 0.5 to 1.5, and the mole ratio of O element and Si element of the silicon-based material of the second coating layer is 0.3 or less.

Accordingly, the present invention is to synergistically control the molar ratio of the O element and the Si element of the silicon-based material in the first coating layer and the second coating layer, so that the first coating layer improves the cycle life of the lithium ion battery, and the second coating layer is lithium. Improve the primary coulombic efficiency and energy density of ion batteries to improve cycle life and energy density of lithium ion batteries.

In an optional embodiment, the molar ratio of O element and Si element of the silicon-based material of the second coating layer is 0.05 to 0.2, which can improve the energy density of the lithium ion battery and also improve the cycle life of the battery.

In any embodiment, 0.8 ≤ A ₁ : A ₂ ≤ 1.2 is satisfied between the weighted gram capacity (A ₁ ) of the first coating layer active material and the weighted gram capacity (A ₂ ) of the second coating layer active material, which is It is possible to reduce the risk of exfoliation of the lithium ion battery during the entire life cycle and improve the performance and safety of the lithium ion battery.

In any embodiment, the weighted gram capacity (A ₁ ) of the first coating layer active material is 500 mAh/g to 1000 mAh/g, and the weighted gram capacity (A ₂ ) of the second coating layer active material is 500 mAh/g to 1000 mAh/g, which can obtain a lithium ion battery with good cycle life and energy density.

In certain embodiments, the content of the silicon-based material in the first coating layer is 18 wt% to 55 wt%, the content of the silicon-based material in the second coating layer is 7 wt% to 21 wt%, and cycle life and energy A lithium ion battery with good density can be obtained.

In certain embodiments, the first coating layer includes a first binder, and the second coating layer includes a second binder, which improves the interfacial adhesion effect of the first coating layer and the second coating layer, and the first coating layer and The risk of peeling of the second coating layer may be further reduced, and safety of the lithium ion battery may be improved.

In certain embodiments, the first binder and the second binder each independently include at least one of polyacrylic acid, polyacrylate, sodium alginate, polyacrylonitrile, polyethylene glycol, carboxymethyl chitosan, and styrenebutadiene rubber .

In certain embodiments, both the first binder and the second binder include a polyacrylate-based binder. The content of the polyacrylate-based binder in the first coating layer is less than that in the second coating layer, and on the basis of satisfying the adhesive effect, the energy density of the battery can be effectively improved and the cost of auxiliary materials can be reduced.

In any embodiment, the content of the polyacrylate-based binder in the first coating layer is 3 wt% to 6 wt%, and the content of the polyacrylate-based binder in the second coating layer is 4 wt% to 7 wt% And, on the basis of satisfying the adhesion effect, it is possible to effectively improve the energy density of the battery and reduce the cost of subsidiary materials.

A second aspect of the present invention provides a secondary battery including the negative electrode plate according to the first aspect of the present invention.

A third aspect of the present invention provides a battery module including the secondary battery according to the second aspect of the present invention.

A fourth aspect of the present invention provides a battery pack including the battery module according to the third aspect of the present invention.

A fifth aspect of the present invention provides an electric device including at least one selected from the secondary battery according to the second aspect of the present invention, the battery module according to the third aspect of the present invention, or the battery pack according to the fourth aspect of the present invention do.

Beneficial effects of the present invention are as follows.

The present invention provides a negative electrode plate, a secondary battery, a battery module, a battery pack, and an electric device. The negative electrode plate includes a first coating layer and a second coating layer. By synergistically controlling the molar ratio of O element and Si element of the silicon-based material in the first coating layer and the second coating layer, the first coating layer improves the cycle life of the lithium ion battery after primary lithium indercalation, and the second coating layer Improving the primary coulombic efficiency and energy density of lithium ion batteries, thereby improving cycle life and energy density of lithium ion batteries. Of course, implementing any product or method of the present invention does not necessarily achieve all of the advantages described above simultaneously.

BRIEF DESCRIPTION OF THE DRAWINGS To describe the technical solutions of the present invention and the prior art more clearly, the following briefly introduces drawings to be used in the embodiments of the present invention and the prior art. In the following description, it is obvious that the drawings are some embodiments of the present invention.
1 is a schematic diagram of a negative electrode plate according to an embodiment of the present invention.
2 is a schematic diagram of a secondary battery according to an embodiment of the present invention.
FIG. 3 is an exploded view of the secondary battery according to one embodiment of the present invention shown in FIG. 2 .
4 is a schematic diagram of a battery module according to an embodiment of the present invention.
5 is a schematic diagram of a battery pack according to an embodiment of the present invention.
FIG. 6 is an exploded view of the battery pack according to one embodiment of the present invention shown in FIG. 5 .
7 is a schematic diagram of an electric device in which a secondary battery is used as a power source according to an embodiment of the present invention.

Hereinafter, embodiments specifically disclosing the negative electrode plate, the positive electrode plate, the secondary battery, the battery module, the battery pack, and the electric device of the present invention will be described in detail with appropriate reference to the accompanying drawings. However, unnecessary detailed descriptions are omitted in some cases. For example, detailed descriptions of well-known information and overlapping descriptions of actually identical structures may be omitted. This is to prevent the following description from being unnecessarily lengthy and to facilitate understanding by those skilled in the art. In addition, the accompanying drawings and the following description are provided so that those skilled in the art can fully understand the present invention, and are not intended to limit the subject matter described in the claims.

A “range” as disclosed herein is defined in the form of a lower limit and an upper limit, and a given range is defined by a selection of one lower limit and one upper limit, the selected lower limit and one upper limit defining the boundaries of the particular range. Ranges defined in this way may or may not include endpoint values and may be in any combination. That is, any lower limit and any upper limit may be combined to form a range. For example, if ranges of 60 to 120 and 80 to 110 are recited for a particular parameter, it should be understood that ranges of 60 to 110 and 80 to 120 are also contemplated. Also, if minimum range values 1 and 2 are listed and maximum range values 3, 4 and 5 are listed, all ranges from 1 to 3, 1 to 4, 1 to 5, 2 to 3, 2 to 4, and 2 to 5 are expected. . In the present invention, unless otherwise specified, the numerical range “a to b” represents an abbreviated representation of the combination of real numbers between a and b, where a and b are both real numbers. For example, a numerical range of "0 to 5" means that all real numbers between "0 and 5" are listed herein, and "0 to 5" is merely an abbreviation for a combination of such numerical values. In addition, when a specific parameter is expressed as an integer of 2 or more, it is the same as disclosed that the parameter is an integer such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, for example.

Unless otherwise specified, all embodiments and optional embodiments of the present invention may be combined with each other to form new technical solutions.

Unless otherwise specified, all technical features and optional technical features of the present invention may be combined with each other to form a new technical solution.

Unless otherwise specified, all steps of the present invention may be performed sequentially or randomly, and are preferably performed sequentially. For example, the method includes steps (a) and (b), wherein the method may include steps (a) and (b) performed sequentially and steps (b) and (b) performed sequentially. indicates that it may contain a). For example, the method mentioned may further include step (c), indicating that step (c) may be added to the method in any order, for example, the method may include steps ( may include a), (b) and (c), may include steps (a), (c) and (b), may include steps (c), (a) and (b), etc. may be

Unless otherwise specified, "comprehensive" and "including" mentioned in the present invention may mean open and closed types. For example, the above “comprehensive” and “include” indicate that other components not listed may be more comprehensive or included, and only the listed components may be included or included.

Unless otherwise specified, the term "or" in the present invention is inclusive. For example, the phrase “A or B” refers to “A, B, or both A and B”. More specifically, A is true (or present) and B is false (or absent); A is false (or absent) and B is true (or present); or any one of the conditions in which both A and B are true (or present) satisfies both conditions “A or B”.

In the process of researching silicon-based material batteries, the present inventors found that silicon-based materials have a great problem with volume expansion during charging and discharging processes, making it difficult for the cycle life of silicon-based material batteries to satisfy application requirements. Silicon-based materials have a low first-order coulombic efficiency, which affects the energy density of silicon-based material batteries. In order to improve the cycle life and energy density of silicon-based material batteries, and to improve the performance of silicon-based material batteries when applied to electrical devices, such as long cruising distance and extended service life, the present invention provides a negative electrode plate, a secondary battery, Battery modules, battery packs and electrical devices are provided.

In one embodiment of the present invention, as shown in FIG. 1 , the present invention provides a negative electrode plate including a first coating layer 1 , a second coating layer 2 and a current collector 3 . One side of the second coating layer 2 is the current collector 3, the other side of the second coating layer 2 is the first coating layer 1, and the first coating layer 1 and the second coating layer 2 are made of a silicon-based material. include The molar ratio of O element and Si element of the silicon-based material of the first coating layer 1 is 0.5 to 1.5, preferably 0.8 to 1.2, and the molar ratio of O element and Si element of the silicon-based material of the second coating layer 2 is 0.3 or less. am.

Although the mechanism is not yet clear, the present inventors found that the negative electrode plate of the present invention includes a first coating layer and a second coating layer, and the molar ratio of O element and Si element of the silicon-based material in the first coating layer and O of the silicon-based material in the second coating layer By synergistically controlling the molar ratio of the element and the Si element within the range of the present invention, the first coating layer improves the cycle life of the lithium ion battery, and the second coating layer improves the primary coulombic efficiency and energy density of the lithium ion battery, It has been unexpectedly found that the cycle life and energy density of lithium ion batteries are overall improved.

The present inventors are not limited to any theory, and in the case of silicon-based negative electrode materials, lithium oxide and lithium silicate (e.g., Li ₂ SiO ₃ , Li ₄ SiO ₄ , Li ₆ Si ₂ O ₇ , etc.) components have a higher share. The presence of these components can effectively alleviate the volume change of the silicon-based material during the lithium indercalation process, effectively improving the degree of rupture and restoration of the solid electrolyte interface (SEI) film during the life cycle of the lithium ion battery, and further improving the quality of the lithium ion battery. It was found that the cycle life was improved. However, the presence of these irreversible lithium deintercalation components reduces the reversible gram capacity of the silicon-based material, further affects the primary coulombic efficiency of the lithium ion battery and causes a certain loss of energy density of the lithium ion battery. Conversely, when the content of oxygen element in the silicon-based material decreases, the silicon-based material expands during the lithium deintercalation process, and the capacity of the silicon-based material rapidly decreases as the number of cycles increases, but the primary Coulombic efficiency of the lithium ion battery high, and the energy density is correspondingly high.

The present inventors are also not limited to any theory, and in the process of charging and discharging the porous electrode, due to the existence of liquid phase ohmic polarization and diffusion polarization, the charging and discharging current is more concentrated from the electrode plate to the side closer to the solution. That is, it was found that the closer the active material particles were to the surface of the electrode plate (ie, the electrolyte side), the greater the throughput of delithiation and lithium indercalation performed by the active material in the charging and discharging process.

Based on this, in the present invention, the first coating layer of the negative electrode plate is installed close to the electrolyte, so that the battery can withstand a large amount of lithium ion treatment during use. In addition, in the first coating layer, the molar ratio of O element and Si element of the silicon-based material is 0.5 to 1.5, and after the primary lithium indercalation, more active materials such as lithium oxide and lithium silicate are formed to buffer the volume expansion, thereby Improves the cycle life of lithium ion batteries. The second coating layer is installed close to the current collector, and the molar ratio of O element and Si element of the silicon-based material of the second coating layer is 0.3 or less, reducing the amount of active lithium consumed during the primary lithium indercalation process of the negative electrode plate, The primary coulombic efficiency and energy density of lithium ion batteries can be improved. The negative electrode plate of the present invention includes the first coating layer and the second coating layer, so that a lithium ion battery has high energy density, primary coulombic efficiency, and cycle life.

In some embodiments, the silicon-based material of the first coating layer of the present invention can be a silicon-oxygen material (denoted as SiO _x ), and the silicon-based material of the second coating layer can be a silicon-oxygen material or a single silicon material.

In some embodiments, the mole ratio of element O to element Si of the silicon-based material of the first coating layer is between 0.8 and 1.2, and the mole ratio of element O and element Si of the silicon-based material of the second coating layer is between 0.05 and 0.2. The present inventors improve the energy density of a lithium ion battery by controlling the molar ratio of O element and Si element of the silicon-based material of the first coating layer and the O element and Si element of the silicon-based material of the second coating layer within the above ranges, It was found that the cycle life of can also be improved together.

In some embodiments, 0.8 ≤ A ₁ : A ₂ ≤ 1.2 is satisfied between the weighted gram capacity (A ₁ ) of the first coating layer active material and the weighted gram capacity (A ₂ ) of the second coating layer active material. In the present invention, the weighted gram capacity (A) of the active material in a specific coating layer represents the weighted value of the reversible lithium deintercalation gram capacity of the silicon-based material and the reversible lithium deintercalation gram capacity of other active ingredients in the active material of the coating layer, The weighted gram capacity (A) is calculated by the expression: A = ∑n _i × x _i , and the unit is mAh/g. where x _i represents the mass ratio of the ith active ingredient to the total active material in the coating layer, and ∑x _i = 1; n _i represents the reversible gram capacity of the ith active ingredient in the corresponding coating layer, in units of mAh/g.

In the case of a composite electrode plate containing both a carbon material and a silicon-based material, the present inventors found that the weighted gram capacity is higher as the proportion of the silicon-based material is higher under the condition that the composition of the silicon-based material is fixed, but the repulsion of the electrode plate in the same charged state this is bigger If the difference in weighted gram capacity between the first coating layer and the second coating layer is too large, in the process of lithium deintercalation of the electrode plate, the difference in expansion stress endured by the first coating layer and the second coating layer is too large, resulting in poor interfacial compatibility between the two coating layers. This may cause a situation in which the first coating layer and the second coating layer are separated and peeled during a full charge state or during a battery life cycle. Therefore, some active materials of the first coating layer may be separated from the conductive network and may not perform lithium deintercalation. Found out that it can cause problems.

In the present invention, by controlling the ratio of the weighted gram capacity (A ₁ ) of the active material of the first coating layer and the weighted gram capacity (A ₂ ) of the active material of the second coating layer within the above range, the electrode plate deinterconnects lithium ions in different capacity attenuation states. During calation, good interfacial compatibility is maintained between the first coating layer and the second coating layer, and the stress difference between the two coating layers is maintained within a small range, thereby reducing the risk of separation of the lithium ion battery during the entire life cycle of the lithium ion battery. and improve the performance and safety of lithium-ion batteries.

In some embodiments, the weighted gram capacity (A ₁ ) of the first coating layer active material is 500 mAh/g to 1000 mAh/g, and the weighted gram capacity (A ₂ ) of the second coating layer active material is 500 mAh/g to 1000 mAh/g. is g. Without being limited by any theory, by synergistically controlling the weighted gram capacity (A ₁ ) of the active material of the first coating layer and the weighted gram capacity (A ₂ ) of the active material of the second coating layer within the above range, the expansion of the negative electrode plate during the cycling process is controlled within an appropriate range, and at the same time obtains a lithium ion battery with high gram capacity and good cycle life and energy density.

In some embodiments, the content of the silicon-based material in the first coating layer is 18 wt% to 55 wt%, and the content of the silicon-based material in the second coating layer is 7 wt% to 21 wt%. Without being limited by any theory, by synergistically controlling the content of the silicon-based material in the first coating layer and the content of the silicon-based material in the second coating layer within the above range, the expansion of the negative electrode plate in the cycling process is controlled within an appropriate range, and at the same time, the gram A lithium ion battery with high capacity and excellent cycle life and energy density is obtained.

In some embodiments, the first coating layer includes a first binder and the second coating layer includes a second binder. In the present invention, the first binder and the second binder may be the same or different. By adding a first binder to the first coating layer and adding a second binder to the second coating layer, the interfacial adhesion effect between the first coating layer and the second coating layer is improved, and the risk of separation between the first coating layer and the second coating layer is further reduced. , can improve the safety of lithium ion batteries.

In the present invention, the first binder and the second binder are not particularly limited as long as they can achieve the object of the present invention. In some embodiments, the first binder and the second binder each independently include at least one of polyacrylic acid, polyacrylate, sodium alginate, polyacrylonitrile, polyethylene glycol, carboxymethyl chitosan, and styrenebutadiene rubber.

In some embodiments, both the first binder and the second binder include a polyacrylate-based binder, and an amount of the polyacrylate-based binder in the first coating layer is less than an amount in the second coating layer. When the first coating layer and the second coating layer of the negative electrode plate of the present invention include a silicon-based material, and both the first binder and the second binder include a polyacrylate-based binder, the polyacrylate-based binder contains the silicon-based material and strong hydrogen. By forming a bond and effectively coating the surface of the silicon-based material, volume expansion of the silicon-based material during charging and discharging can be alleviated. The inventors have found that the volume expansion of the lithium ion battery during cycling is smaller than that of the second coating layer due to the high oxygen to silicon molar ratio of the silicon-based material in the first coating layer. Therefore, by controlling the content of the polyacrylate-based binder in the first coating layer to be less than that in the second coating layer, the energy density of the battery can be improved and the cost of subsidiary materials can be reduced on the basis of satisfying the adhesive effect.

In some embodiments, the content of the polyacrylate-based binder in the first coating layer is 3 wt% to 6 wt%, and the content of the polyacrylate-based binder in the second coating layer is 4 wt% to 7 wt%. The present inventors are not limited to any theory, and by controlling the content of the polyacrylate-based binder in the first coating layer and the second coating layer within the above range, the energy density of the battery is effectively improved on the basis of satisfying the adhesive effect and the cost of subsidiary materials is reduced. found to be able to reduce it.

In the present invention, the manufacturing method of the silicon-based material is not particularly limited, and may be manufactured by, for example, the following steps.

Silicon dioxide powder and single silicon powder are obtained through a high-temperature gas phase reaction in a non-oxidizing gas atmosphere, and the ratio of oxygen and silicon elements in the obtained silicon-based material is controlled by adjusting the ratio of silicon dioxide powder and single silicon powder. In the present invention, the particle diameter of the silicon dioxide powder and the single silicon powder is not particularly limited as long as it can satisfy the requirements of the present invention, for example, the average particle diameter of the silicon dioxide powder is 1 μm to 10 μm, and the single silicon powder The average particle diameter of is 1 μm to 10 μm. In the present invention, the non-oxidizing gas atmosphere is not particularly limited, and may be, for example, an argon gas or hydrogen gas atmosphere. In the present invention, the temperature of the gas phase reaction is not particularly limited as long as it can satisfy the requirements of the present invention, for example, the temperature is 1300 ° C to 1400 ° C.

In some embodiments, the prepared silicon oxygen material can be further coated or blended with other active materials for use in lithium ion batteries.

In addition, the secondary battery, battery module, battery pack, and electric device of the present invention will be described below with appropriate reference to the drawings.

One embodiment of the present invention provides a secondary battery including the negative electrode plate according to any of the above embodiments. The secondary battery of the present invention may mean any lithium ion battery according to the above embodiment.

Generally, a secondary battery includes a positive electrode plate, a negative electrode plate, an electrolyte, and a separator. During the charging and discharging process of the battery, active ions intercalate and deintercalate repeatedly between the positive electrode plate and the negative electrode plate. The electrolyte acts as an ion transfer between the positive electrode plate and the negative electrode plate. The separator is installed between the positive electrode plate and the negative electrode plate, and mainly serves to prevent a short circuit between the positive electrode and the negative electrode, and allows ions to pass through.

[Anode pole plate]

The positive electrode plate includes a positive electrode current collector and a positive electrode film layer provided on at least one surface of the positive electrode current collector. As an example, the positive electrode current collector has two opposing surfaces in its own thickness direction, and the positive electrode film layer is provided on any one or both of the two opposing surfaces of the positive electrode current collector.

In some embodiments, a metal foil or a composite current collector may be used as the cathode current collector. For example, aluminum foil may be used as the metal foil. The composite current collector may include a polymer material base layer and a metal layer formed on at least one surface of the polymer material base layer. The composite current collector is a metal material (aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) It can be formed by forming on a substrate) such as polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE).

In some embodiments, a cathode active material for a battery known in the art may be used as the cathode active material. As an example, the cathode active material may include at least one of an olivine-structured lithium-containing phosphate, a lithium transition metal oxide, and each of these modified compounds. However, the present invention is not limited to these materials, and other conventional materials that can be used as a positive electrode active material for a battery may also be used. These cathode active materials may be used alone or in combination of two or more. Here, examples of the lithium transition metal oxide include lithium cobalt oxide (eg, LiCoO ₂ ), lithium nickel oxide (eg, LiNiO ₂ ), lithium manganese oxide (eg, LiMnO ₂ , LiMn ₂ O ₄ ), Lithium Nickel Cobalt Oxide, Lithium Manganese Cobalt Oxide, Lithium Nickel Manganese Oxide, Lithium Nickel Cobalt Manganese Oxide (eg LiNi _1/3 Co _1/3 Mn _1/3 O ₂ (can also be abbreviated as NCM ₃₃₃ ), LiNi _0.5 Co _0.2 Mn _0.3 O ₂ (may be abbreviated as NCM ₅₂₃ ), LiNi _{O. 5} Co _0.25 Mn _0.25 O ₂ (may be abbreviated as NCM ₂₁₁ ), LiNi _0.6 Co _0.2 Mn _0.2 O ₂ (abbreviated as NCM ₆₂₂ may be), LiNi _0.8 Co _0.1 Mn _0.1 O ₂ (which may be abbreviated as NCM ₈₁₁ ), lithium nickel cobalt aluminum oxide (eg, LiNi _0.85 Co _0.15 Al _0.05 O ₂ ), and modified compounds thereof. Examples of the olivine structure lithium-containing phosphate include lithium iron phosphate (eg, LiFePO ₄ (also abbreviated as LFP)), a composite material of lithium iron phosphate and carbon, lithium manganese phosphate ( For example, at least one of LiMnPO ₄ ), a composite material of lithium manganese phosphate and carbon, lithium iron manganese phosphate, and a composite material of lithium iron manganese phosphate and carbon is included, but is not limited thereto.

In some embodiments, the anode film layer may optionally further include a binder. By way of example, the binder is polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetra It may include at least one of a fluoroethylene terpolymer, a tetrafluoroethylene-hexafluoropropylene copolymer, and a fluorine-containing acrylate resin.

In some embodiments, the anode film layer may optionally further include a conductive agent. As an example, the conductive agent may include at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

In some embodiments, a positive electrode slurry is prepared by dispersing the above-described components for preparing a positive electrode plate, such as a positive electrode active material, a conductive agent, a binder, and any other components, in a solvent (eg, N-methylpyrrolidone). After forming, coating the positive electrode slurry on the positive electrode current collector, it can be manufactured through a method of obtaining a positive electrode plate through processes such as drying and cold pressing.

[Cathode plate]

In some embodiments, a metal foil or a composite current collector may be used as the negative current collector of the negative electrode plate. For example, copper foil may be used as the metal foil. The composite current collector may include a polymer material base layer and a metal layer formed on at least one surface of the polymer material substrate. The composite current collector is a metal material (copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) It can be formed by forming on a substrate such as polybutylene terephthalate (PBT), polystyrene (PS), or polyethylene (PE).

In some embodiments, the negative electrode plate can be manufactured in the following manner. preparing a first negative electrode slurry and a second negative electrode slurry; First, the second negative electrode slurry is coated on the current collector to form a second coating layer, and then the first negative electrode slurry is coated on the surface of the second coating layer to form the first coating layer. Alternatively, at the time of coating, the first negative electrode slurry and the second negative electrode slurry are simultaneously coated on the current collector using a double layer coating device; A negative electrode plate is obtained through processes such as drying and cold pressing. In the negative electrode plate, one side of the second coating layer is the current collector, and the other side of the second coating layer is the first coating layer.

[electrolyte]

The electrolyte acts as an ion transfer between the positive electrode plate and the negative electrode plate. The present invention is not specifically limited to the type of electrolyte, and may be selected as necessary. For example, electrolytes can be liquids, gels or all solids.

In some embodiments, the electrolyte uses an electrolyte solution. The electrolyte solution includes an electrolyte salt and a solvent.

In some embodiments, the electrolyte salt is lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bisfluorosulfonimide, lithium bistrifluoromethanesulfonimide, lithium trifluoro romethanesulfonate, lithium difluorophosphate, lithium difluorooxalate borate, lithium dioxalate borate, lithium difluorobisoxalate phosphate and lithium tetrafluorooxalate phosphate.

In some embodiments, the solvent is ethylenecarbonate, propylene carbonate, methylethylcarbonate, diethylcarbonate, dimethyl carbonate, dipropyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, butylene carbonate, fluoroethylenecarbonate, methyl formate, methyl Acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, 1,4-butyrolactone, sulfolane, dimethyl sulfone, methyl ethyl sulfone and diethyl sulfone It may be selected from at least one of

In some embodiments, the electrolyte solution may optionally further include an additive. For example, the additive may include a negative electrode film additive, a positive electrode film additive, and may improve certain performance of the battery, such as an additive to improve the overcharge performance of the battery, an additive to improve the high temperature or low temperature performance of the battery. Additives may be further included.

[Separator]

In some embodiments, the secondary battery may further include a separator. In the present invention, the type of separator is not particularly limited, and a separator having a known porous structure having excellent chemical stability and mechanical stability may be selected.

In some embodiments, the material of the separator may be selected from at least one of glass fiber, nonwoven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The separator may be a single-layer film or a multi-layer composite film, but is not particularly limited. When the separator is a multilayer composite film, the materials of each layer may be the same or different, but are not particularly limited.

In some embodiments, the positive electrode plate, the negative electrode plate, and the separator may be manufactured as an electrode assembly through a winding process or a lamination process.

In some embodiments, a secondary battery may include an outer packaging. The outer packaging is for packaging the electrode assembly and the electrolyte.

In some embodiments, the outer packaging of the secondary battery may be a hard case such as a hard plastic case, an aluminum case, or a steel case. The external packaging of the lithium ion battery may be a soft package such as a bag-type soft package. The material of the soft package may be a plastic such as polypropylene, polybutylene terephthalate, or polybutylene succinate.

The present invention is not particularly limited to the shape of the secondary battery, and may be cylindrical, rectangular, or any other shape. For example, FIG. 2 shows one exemplary quadrangular structured secondary battery 5 .

In some embodiments, referring to FIG. 3 , the outer packaging may include case 51 and cover plate 53 . Here, the case 51 may include a bottom plate and side plates connected to the bottom plate, and the bottom plate and the side plates are surrounded to form an accommodation cavity. The case 51 has an opening communicating with the accommodating cavity, and a cover plate 53 may be installed to cover the opening to seal the accommodating cavity. The positive electrode plate, the negative electrode plate, and the separator may be formed as the electrode assembly 52 through a winding process or a lamination process. An electrode assembly 52 is packaged within the receiving cavity. An electrolyte solution is impregnated into the electrode assembly 52 . The number of electrode assemblies 52 included in the secondary battery 5 may be one or more, and a person skilled in the art may select one according to specific needs.

In some embodiments, the secondary battery may be assembled into a battery module, and the number of lithium ion batteries included in the battery module may be one or more, and a specific number may be selected by a person skilled in the art according to the application and capacity of the battery module.

4 shows one exemplary battery module 4 . Referring to FIG. 4 , in the battery module 4 , a plurality of secondary batteries 5 may be sequentially arranged along the longitudinal direction of the battery module 4 . Of course, it may be arranged according to any other manner. In addition, the plurality of secondary batteries 5 may be fixed by fasteners.

Optionally, the battery module 4 may further include a case having an accommodation space in which a plurality of secondary batteries 5 are accommodated.

In some embodiments, the battery module may also be assembled into a battery pack, and the number of battery modules included in the battery pack may be one or more, and a specific number may be selected by a person skilled in the art according to the application and capacity of the battery pack.

5 and 6 show one exemplary battery pack 10 . Referring to FIGS. 5 and 6 , the battery pack 10 may include a battery box and a plurality of battery modules 4 installed in the battery box. The battery box includes an upper box body 11 and a lower box body 12, and the upper box body 11 is installed to cover the lower box body 12, creating an airtight space for accommodating the battery module 4. can form A plurality of battery modules 4 may be arranged in a battery box in any manner.

In addition, the present invention further provides an electric device including at least one of the secondary battery, battery module or battery pack provided in the present invention. The secondary battery, battery module, or battery pack may be used as a power source of the device and may be used as an energy storage unit of the electric device. The electric device may include a mobile device (eg, a mobile phone, a laptop computer, etc.), an electric vehicle (eg, a pure electric vehicle, a hybrid electric vehicle, a plug-in hybrid electric vehicle, an electric bicycle, an electric scooter, an electric golf cart, an electric truck) etc.), electric trains, ships and satellites, energy storage systems, etc.

The electric device may select a secondary battery, a battery module, or a battery pack according to usage needs.

7 shows one exemplary electrical device. The electric device is a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle. In order to meet the requirements for high power and high energy density of the secondary battery for the electric device, a battery pack or battery module may be used.

As another example, the device may be a mobile phone, tablet computer, notebook computer, or the like. The device is typically required to be light, thin, and light, and a secondary battery may be used as a power source.

Example

Hereinafter, embodiments of the present invention will be described. It should be understood that the examples described below are only for interpreting the present invention as illustrative and are not intended to limit the scope of the present invention. If specific techniques or conditions are not specified in the examples, they are performed according to techniques or conditions described in literature in the art or product specifications. Reagents or instruments for which manufacturers are not specified are commercially available commercially available products.

Example 1

<Manufacture of positive electrode plate>

After mixing LiNi _0.8 Co _0.1 Mn _0.1 O ₂ as a cathode active material, conductive carbon black as a conductive agent, and polyvinylidene fluoride (PVDF) as a binder in a mass ratio of 96:2:2, N-methylpyrrolidone (as a solvent) NMP) was added, and the system was stirred under the action of a vacuum mixer until it was uniform to obtain a positive electrode slurry with a solid content of 75 wt%. The positive electrode slurry is uniformly coated on one side of aluminum foil having a thickness of 12 μm, dried at 120 ° C, and then cold pressed to obtain a positive electrode plate having a thickness of 60 μm of the positive electrode active material layer, followed by processes such as tab forming and slitting Through this, an anode plate was obtained.

<Manufacture of negative electrode plate>

<Preparation of the first negative electrode slurry>

After mixing the first anode active material, artificial graphite as a carbon material, conductive carbon black as a conductive agent, and sodium polyacrylate as a binder in a mass ratio of 18:77:2:3, deionized water was added as a solvent, and when the system became uniform was stirred under the action of a vacuum mixer to obtain a first negative electrode slurry having a solid content of 50 wt%.

<Preparation of the second negative electrode slurry>

After mixing the second anode active material, artificial graphite as a carbon material, conductive carbon black as a conductive agent, and sodium polyacrylate as a binder in a mass ratio of 7:87:2:4, deionized water was added as a solvent, and when the system became uniform was stirred under the action of a vacuum mixer to obtain a second negative electrode slurry having a solid content of 50 wt%.

<Manufacture of negative electrode plate including first coating layer and second coating layer>

Using the double layer coating process, the prepared first negative electrode slurry and the second negative electrode slurry are simultaneously coated on one side of a copper foil having a thickness of 8 μm, dried at 110 ° C., and then cold-pressed to obtain the thickness of the first coating layer and the second negative electrode slurry. After obtaining a negative electrode plate having a thickness of 25 μm, respectively, the negative electrode plate was obtained through processes such as tab forming and slitting.

<Preparation of Electrolyte>

In an environment where the water content is less than 10 ppm, non-aqueous organic solvents such as ethylene carbonate, methyl ethyl carbonate, and diethyl carbonate are mixed in a volume ratio of 1: 1: 1 to obtain an electrolyte solvent, and then LiPF ₆ , a lithium salt, is added to the mixed solvent. It was dissolved to prepare an electrolyte solution having a lithium salt concentration of 1 mol/L.

<Manufacture of separation membrane>

As the separator, a polyethylene film having a thickness of 9 μm was selected and slit to an appropriate width according to the size of the positive electrode plate and the negative electrode plate before use.

<Manufacture of lithium ion battery>

The positive electrode plate, the separator, and the negative electrode plate are sequentially stacked, the separator is placed between the positive electrode plate and the negative electrode plate to serve as insulation, and then wound to obtain an electrode assembly. After putting the electrode assembly in an external packaging case and drying it, electrolyte is injected, and a lithium ion battery is obtained through processes such as vacuum packaging, leaving, chemical formation, and molding.

Examples 2 to 11

In <Production of the negative electrode plate>, as shown in Table 1, the molar ratio of O element and Si element was adjusted in the first negative electrode slurry, and the molar ratio of O element and Si element in the second negative electrode slurry was adjusted; Adjust the values of A ₁ , A ₂ and A ₁ : A ₂ as shown in Table 2; As shown in Table 3, the share of the first negative electrode active material in the first slurry, the share of the second negative electrode active material in the second slurry, the type and share of the binder in the first slurry, the type and share of the binder in the second slurry, the first It is the same as Example 1 except that the share of artificial graphite and conductive carbon black in the anode slurry and the share of artificial graphite and conductive carbon black in the second anode slurry are adjusted.

Example 12

In <Manufacture of positive electrode plate> and <Manufacture of negative electrode plate>, a double-sided coating process was applied to the positive electrode active material layer and the negative electrode active material layer, respectively, that is, the active material layers were installed on both sides of the positive electrode current collector and the negative electrode current collector. Except for the same as Example 1. Here, the active material layers on both sides of the negative current collector include a first coating layer and a second coating layer, respectively.

Comparative Example 1

The rest is the same as in Example 2 except that <Manufacture of negative electrode plate> is different from Example 2.

<Manufacture of negative electrode plate>

After mixing the first anode slurry and the second cathode slurry of Example 2 in a mass ratio of 1: 1 to obtain a mixed slurry, the mixed slurry was coated on one side of copper foil having a thickness of 8 μm, and dried at 110 ° C. Then, cold pressing was performed to obtain a negative electrode plate having a negative electrode active material layer thickness of 50 μm, and then the negative electrode plate was obtained through processes such as tab forming and slitting.

Comparative Examples 2 to 6

In <Production of the negative electrode plate>, as shown in Table 1, the molar ratio of O element and Si element was adjusted in the first negative electrode slurry, and the molar ratio of O element and Si element in the second negative electrode slurry was adjusted; Adjust the values of A ₁ , A ₂ and A ₁ : A ₂ as shown in Table 2; As shown in Table 3, the share of the first negative electrode active material in the first slurry, the share of the second negative electrode active material in the second slurry, the type and share of the binder in the first slurry, the type and share of the binder in the second slurry, the first It is the same as Example 1 except that the share of artificial graphite and conductive carbon black in the anode slurry and the share of artificial graphite and conductive carbon black in the second anode slurry are adjusted.

The related parameters of Examples 1 to 12 and Comparative Examples 1 to 6 are shown in Tables 1 to 3 below. Here, the mole ratio of O element and Si element in the first negative electrode slurry and the mole ratio of O element and Si element in the second negative electrode slurry are as shown in Table 1; The values of A ₁ , A ₂ and A ₁ : A ₂ are as shown in Table 2. The share of the first negative electrode active material in the first slurry, the share of the second negative electrode active material in the second slurry, the type and share of the binder in the first slurry, the type and share of the binder in the second slurry, the artificial graphite and The share of conductive carbon black and the share of artificial graphite and conductive carbon black in the second anode slurry are shown in Table 3.

[Table 1] Related parameters of Examples 1 to 12 and Comparative Examples 1 to 6

First cathode slurry Second cathode slurry Existence of the first coating layer and the second coating layer O: Si ratio of the first negative electrode active material O: Si ratio of the second negative electrode active material Example 1 1:1 0.1:1 yes Example 2 1:1 0.1:1 yes Example 3 1:1 0.1:1 yes Example 4 1:1 0.1:1 yes Example 5 1.5:1 0.3 : 1 yes Example 6 0.5 : 1 0.05 : 1 yes Example 7 1:1 0.1:1 yes Example 8 1:1 0.1:1 yes Example 9 1:1 0 : 1 (single silicon) yes Example 10 1:1 0.1:1 yes Example 11 1:1 0.1:1 yes Example 12 1:1 0.1:1 yes Comparative Example 1 1:1 0.1:1 no Comparative Example 2 1:1 1:1 yes Comparative Example 3 0.1:1 1:1 yes Comparative Example 4 1.85:1 0.1:1 yes Comparative Example 5 1:1 0.1:1 yes Comparative Example 6 1:1 0.1:1 yes

[Table 2] Related parameters of Examples 1 to 12 and Comparative Examples 1 to 6

A ₁ : A _{2 A1} (mAh/g) _A2 (mAh/g) Example 1 1.01 549 546 Example 2 1.01 605 601 Example 3 1.01 860 853 Example 4 1.02 964 941 Example 5 1.02 565 553 Example 6 1.03 690 672 Example 7 0.81 605 743 Example 8 1.20 686 574 Example 9 1.00 605 602 Example 10 1.01 605 601 Example 11 1.02 607 598 Example 12 1.01 549 546 Comparative Example 1 1.01 605 601 Comparative Example 2 1.00 605 605 Comparative Example 3 0.99 601 605 Comparative Example 4 0.99 460 467 Comparative Example 5 0.64 549 853 Comparative Example 6 1.58 860 546

[Table 3] Related parameters of Examples 1 to 12 and Comparative Examples 1 to 6

In addition, performance tests were performed on the lithium ion batteries prepared in Examples 1 to 12 and Comparative Examples 1 to 6, and the button-type batteries prepared using the anode active materials of Examples 1 to 12 and Comparative Examples 1 to 6. did The test results are shown in Table 4 below.

Energy density test :

The test temperature was 25 ° C., and the lithium ion battery prepared in each Example and Comparative Example was first charged to 4.25V at a constant current of 0.33C rate, then charged to 0.05C at a constant voltage, left for 5 minutes, and then 0.33C discharged to 2.8V. After recording the discharge energy, the discharge energy density at 0.33 C was calculated according to the following formula energy density (Wh/kg) = discharge energy (Wh)/weight of the electrochemical device (kg).

Cycle life test :

The test temperature is 25 ° C., and the lithium ion battery prepared in each example and comparative example is charged to 4.25V with a constant current of 0.33C, charged to 0.05C at a constant voltage, left for 10 minutes, and then charged at 2.8V at 0.33C. discharged to V. The capacity obtained in this step is the initial capacity, and a cycle test was performed by charging up to 4.25V with a constant current of 0.33C, charging up to 0.05C at a constant voltage of 4.25V, and discharging up to 2.8V at 0.33C. The dose decay curve was obtained by taking the ratio of the dose at each stage to the initial dose. The cycle life of the battery was recorded as the number of cycles at 25° C. when the capacity retention rate reached 80%.

First charge and discharge efficiency test :

A charge/discharge test was performed with a Neware CT-4000 power battery detection system for the lithium ion battery prepared in each Example and Comparative Example, and the first charge/discharge efficiency of the lithium ion battery was calculated.

The first efficiency calculation method is (C ₁ /C ₂ ) × 100%, where C ₁ is the capacity of the lithium-ion battery at the first charge, and the charging process is 4.25 C after charging with 0.33 C constant current to a voltage of 4.25 V It was charged up to 0.05C with a V constant voltage. After first charging the lithium ion battery according to the process described above, C ₂ was discharged at 0.33 C until the voltage reached a capacity corresponding to 2.8V.

Weighted gram capacity test :

The weighted gram capacity of the different coating layers of the negative electrode plate in Examples 1 to 12 and Comparative Examples 1 to 6 was obtained in the following manner.

Anode active material (e.g., silicon-based material, artificial graphite material), conductive carbon black as a conductive agent, and PVDF (polyvinylidene fluoride) as a binder are mixed in a ratio of 80: 10: 10, deionized water is added, and stirring Thus, a slurry having a solid content of 50 wt% was formed, and a coating layer having a thickness of 50 μm was coated on the surface of the current collector using a scraper. After drying in a vacuum drying oven at 85° C. for 12 hours, it was cut into circular electrode plates having a diameter of 1 cm in a drying environment using a punching machine. In a glove box, a metal lithium electrode plate was used as a counter electrode, a PE (polyethylene) composite film was selected as a separator, and an electrolyte was added to assemble it into a button-type battery. The reversible gram capacity of the active ingredient tested was was calculated through The weighted gram capacity of the active material of the first coating layer or the second coating layer is calculated by the following expression A = x ₁ x n ₁ + x ₂ x n ₂ (mAh/g). Here, x ₁ and x ₂ are the mass ratios of the silicon-based material and the carbon material in the active material, respectively, x ₁ + x ₂ = 1, n ₁ represents the reversible gram capacity of the silicon-based material, the unit is mAh/g, and n ₂ represents the reversible gram capacity of the artificial graphite material, and the unit is mAh/g.

Table 4: Performance test results of Examples 1 to 12 and Comparative Examples 1 to 6

First charge and discharge efficiency Energy density (Wh/kg) Cycle life (cycles) Example 1 90% 280 1300 Example 2 88% 300 1000 Example 3 86% 330 700 Example 4 84% 360 550 Example 5 83% 270 1400 Example 6 89% 320 850 Example 7 88% 300 900 Example 8 88% 300 950 Example 9 90% 305 950 Example 10 88% 300 850 Example 11 88% 300 900 Example 12 90% 285 1300 Comparative Example 1 88% 300 550 Comparative Example 2 72% 250 1050 Comparative Example 3 88% 300 200 Comparative Example 4 76% 250 1200 Comparative Example 5 87% 300 600 Comparative Example 6 85% 300 550

According to the above results, the negative electrode plates of the lithium ion batteries of Examples 1 to 12 include a first coating layer and a second coating layer, that is, have a multilayer structure. Here, one side of the second coating layer is a current collector, and the other side of the second coating layer is the first coating layer. It can be seen that the molar ratio of O element and Si element of the silicon-based material in the first coating layer and the second coating layer is within the scope of the present invention, and the lithium ion battery has excellent energy density and primary coulombic efficiency and good cycle life. .

From Examples 1 to 4, after determining the oxygen and silicon element ratio of the silicon-based material of each coating layer of the negative electrode plate, as the content of the silicon-based material in the negative electrode plate increases, the weighted gram capacity of the negative electrode plate is improved, further lithium ion battery It can be seen that the energy density of

From Examples 2, 5, 6, and 9, when the occupancy of the silicon-based material is relatively fixed in each coating layer of the negative electrode plate, as the molar ratio of oxygen and silicon element of the silicon-based material in the first coating layer and the second coating layer increases, It can be seen that the cycle life of the ion battery improved, and the energy density and primary coulombic efficiency showed a decreasing trend, but the decrease was not clear.

From Examples 1 to 12, and also by controlling the occupancy of the silicon-based material in each coating layer, the ratio A ₁ : A 2 of the weighted gram capacity (A ₁ ) of the first coating layer and the weighted gram capacity (A ₂ ) of the second coating layer _is Within the scope of the present invention, it can be seen that lithium ion batteries combine high energy density, high primary coulombic efficiency and long cycle life.

From Examples 1 to 9 and 11 to 12, furthermore, when both the first coating layer and the second coating layer use a polyacrylate-based binder (eg, sodium polyacrylate), the polyacrylate-based binder in the first coating layer When the content of is less than the content in the second coating layer, the lithium ion battery may exhibit better cycle life.

The type and content of the binder in the first coating layer and the second coating layer generally affect the performance of the lithium ion battery. From Examples 1 to 12, it can be seen that a lithium ion battery having excellent energy density and primary coulombic efficiency and good cycle life can be obtained as long as the type and content of the binder are within the scope of the present invention.

In comparison, the negative electrode plate of Comparative Example 1 was obtained by coating after uniformly mixing the slurry of the first coating layer and the slurry of the second active coating layer of Example 2, and the type and composition of the silicon-based material of the negative electrode plate are All are the same in the direction perpendicular to the whole, and therefore the energy density and primary coulombic efficiency of Comparative Example 1 are basically the same as those of Example 2. However, since the double-coated layer structure of the present invention is not provided, in the lithium ion battery, the reversible capacity of the silicon-based material (i.e., the second negative electrode active material) having a ratio of oxygen and silicon elements of 0.1:1 on the surface close to the current collector rapidly increases during the cycling process. Attenuated, the cycle life of the lithium ion battery of Comparative Example 1 was only 550 cycles, and the cycle life was not effectively improved, making it difficult to meet the requirements of many application scenarios for the life of the lithium ion battery.

In the first coating layer and the second coating layer used in Comparative Example 2, the oxygen and silicon element molar ratios of the silicon-based material were all 1:1, and the primary coulombic efficiency of the obtained lithium ion battery decreased to 72%, and the energy of the lithium ion battery The density is only 250 Wh/kg, which does not have a significant advantage in terms of energy density compared to lithium-ion batteries that do not use silicon-based materials for the negative electrode, so it is difficult to meet the scenario requirements for high energy density.

The molar ratio of oxygen and silicon elements in the first coating layer and the second coating layer used in the negative electrode plate of Comparative Example 3 is opposite to that in Example 2, and the reversible capacity of the obtained lithium ion battery is rapidly attenuated in the cycling process, and the cycle of the lithium ion battery The lifetime is only 200 cycles, and the cycle life is not effectively improved, making it difficult to meet the requirements of many application scenarios for lithium-ion battery life.

In the first coating layer used in Comparative Example 4, the oxygen and silicon element ratio of the silicon-based material is 1.85: 1, the primary coulombic efficiency of the obtained lithium ion battery is extremely low, and the energy density of the battery is only 250 Wh/kg , compared with lithium-ion batteries that do not use silicon-based materials, they have no advantage, making it difficult to satisfy the scenario's requirement for high energy density.

In Comparative Examples 5 and 6, the ratio of the weighted gram capacity (A ₁ ) of the first coating layer of the negative electrode plate to the weighted gram capacity (A ₂ ) of the second coating layer is out of the scope of the present invention, and the cycle life of the lithium ion battery is reduced. . This may be due to the large difference in expansion stress between the first coating layer and the second coating layer in the lithium deintercalation process of the lithium ion batteries of Comparative Examples 5 and 6, and the interfacial compatibility between the first coating layer and the second coating layer is inferior. Even a part of the first coating layer is detached from the second coating layer, and some active materials of the first coating layer may be detached from the conductive network during the cycling process, affecting the cycle life of the lithium ion battery.

It should be noted that the present invention is not limited to the above embodiment. The above-described embodiment is only an example, and all embodiments having the same configuration as the technical idea and exhibiting the same action and effect within the scope of the technical solution of the present invention are included in the technical scope of the present invention. In addition, various modifications that can be conceived by those skilled in the art can be made to the embodiments without departing from the gist of the present invention, and other forms formed by combining some of the components of the embodiments are also included within the scope of the present invention.

1: first coating layer
2: second coating layer
3: current collector
4: battery module
5: secondary battery
10: battery pack
11: upper box body
12: lower box body
51: case
52: electrode assembly
53: cover plate.

Claims (13)

As a negative electrode plate,
It includes a first coating layer, a second coating layer and a current collector, one side of the second coating layer is the current collector, the other side of the second coating layer is the first coating layer, and the first coating layer and the second coating layer are silicon-based. A negative electrode plate comprising a material, wherein the molar ratio of O element and Si element of the silicon-based material of the first coating layer is 0.5 to 1.5, and the molar ratio of O element and Si element of the silicon-based material of the second coating layer is 0.3 or less. According to claim 1,
The negative electrode plate having a molar ratio of O element and Si element of the silicon-based material of the second coating layer is 0.05 to 0.2. According to claim 1 or 2,
A negative electrode plate that satisfies 0.8 ≤ A ₁ : A ₂ ≤ 1.2 between the weighted gram capacity (A ₁ ) of the active material of the first coating layer and the weighted gram capacity (A ₂ ) of the active material of the second coating layer. According to claim 3,
A weighted gram capacity (A ₁ ) of the active material of the first coating layer is 500 mAh/g to 1000 mAh/g, and a weighted gram capacity (A ₂ ) of the active material of the second coating layer is 500 mAh/g to 1000 mAh/g. play. According to any one of claims 1 to 4,
The content of the silicon-based material in the first coating layer is 18 wt% to 55 wt%, and the content of the silicon-based material in the second coating layer is 7 wt% to 21 wt%. According to any one of claims 1 to 5,
The negative electrode plate of claim 1 , wherein the first coating layer includes a first binder, and the second coating layer includes a second binder. According to claim 6,
The first binder and the second binder each independently include at least one of polyacrylic acid, polyacrylate, sodium alginate, polyacrylonitrile, polyethylene glycol, carboxymethyl chitosan, and styrene-butadiene rubber. According to claim 6,
The first binder and the second binder both include a polyacrylate-based binder, and an amount of the polyacrylate-based binder in the first coating layer is less than an amount in the second coating layer. According to claim 8,
The content of the polyacrylate-based binder in the first coating layer is 3 wt% to 6 wt%, and the content of the polyacrylate-based binder in the second coating layer is 4 wt% to 7 wt%. As a secondary battery,
A secondary battery comprising the negative electrode plate according to any one of claims 1 to 9. As a battery module,
A battery module comprising the secondary battery according to claim 10 . As a battery pack,
A battery pack comprising the battery module according to claim 11 . As an electrical device,
An electric device including at least one selected from the secondary battery according to claim 10, the battery module according to claim 11, or the battery pack according to claim 12.

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